OFDM and OFDMA wireless communication systems under IEEE 802.16 use a network of base stations to communicate with wireless devices (i.e., mobile stations) registered for services in the systems based on the orthogonality of frequencies of multiple subcarriers and can be implemented to achieve a number of technical advantages for wideband wireless communications, such as resistance to multipath fading and interference. Each base station (BS) emits and receives radio frequency (RF) signals that convey data to and from the mobile stations (MS).
In such systems, a security protocol often requires the network and mobile station share valid security keys such as AK (authorization key) and TEK (traffic encryption key) keys. These security keys are used for both management connections, as well as transport connections. Different security keys have different lifetimes and the standard requires the network and mobile station to refresh the keys periodically, depending on the length of their lifetimes. In the event that a security key lifetime expires before the key is refreshed, communication between mobile station and the network will be halted until new security key is successfully negotiated.
Unfortunately, negotiating a new key may be a relatively lengthy process that detracts from the user experience. In the event that a security key lifetime expires during a hand-over between base stations, communication between the mobile station and the new base station will be delayed until a new security key is successfully negotiated, thus adding to any break in traffic caused by the hand-over.